For a bird with a reputation as an aggressive predator, the double-crested cormorant spends a lot of time just sitting around. These gregarious birds have been arriving in significant numbers again …
For a bird with a reputation as an aggressive predator, the double-crested cormorant spends a lot of time just sitting around. These gregarious birds have been arriving in significant numbers again this year, and the persistent ice cover on most area lakes has given them more reason than ever just to hang out.
While anglers in our area often see cormorants as unwelcome competition (and they certainly can be), I can’t help but have a bit of grudging respect for birds that are so well adapted to their watery niche. The cormorants are actually a large family of mostly sea-going birds that are famed for their ability to dive deep in search of fish. They are remarkably successful at what they do, and that’s part of the reason that they can pose challenges for smaller-scale fisheries, like Lake Vermilion.
The double-crested cormorant is the only species regularly found on inland waters in North America, and it’s the only variety you’re likely to find in our region. They’re easily recognized by their large size, black feathers, and orange patch of bare skin around the bill and face. Their double crest, when raised, gives them a somewhat comical appearance when viewed straight on— like some old guy with bushy eyebrows run amok.
The cormorant derives its name from a combination of two Latin words, corvus and marinus, which essentially translates as “raven of the sea.” While seemingly apt, due mostly to size and color, the cormorant is a specialized hunter, not a generalist like a raven. When it comes to fishing, the cormorant is remarkably adept. They’re spectacular swimmers and can easily dive to the bottom of any lake in our region. Underwater, they propel themselves mostly with their large webbed feet, while their wings do most of the steering. Their hooked beaks allow them to firmly grasp their prey, which in our region appears to be comprised mostly of perch, although any small fish will do in most cases.
Anyone who has observed cormorants in action has no doubt noticed that these birds ride very low in the water, with sometimes just their head and snake-like neck protruding above the surface. Cormorants have very little of the oil that normally coats the feathers of other birds, which means their feathers get wet, significantly reducing their buoyancy. This actually helps the cormorant dive deeper, but it means they spend a lot amount of time sitting in exposed locations, sometimes with their wings spread, to dry their feathers more quickly. They’re gregarious by nature, which means they like to do this in large groups.
Like a lot of bird species that rely on the aquatic food chain, the double-crested cormorant has been rebounding in recent decades. Years of persecution by humans and the effects of DDT-use had decimated their numbers by the 1960s. Since then, their numbers have rebounded significantly in some areas, particularly in the Great Lakes region.
That rebound can be viewed differently depending on your perspective. For people who remember when cormorant populations were extremely low, the species’ rebound can look like an out-of-control population growth. Yet it may be, instead, that their current numbers simply reflect prior levels of population before human disturbance and chemical impacts.
In either case, the widespread dislike of cormorants has put tremendous pressure on federal wildlife managers to allow for population controls on the species. For a few years, those controls had allowed federal officials to shoot cormorants on Lake Vermilion and on other large lakes in Minnesota and to oil their eggs to suffocate the developing chicks. But a lawsuit challenging the decision succeeded in having the federal control order overturned, which has put at least a temporary halt on the cormorant control efforts in the U.S., including here in Minnesota.
Controlling cormorants is made easier by the facts that they nest colonially and that they spend so much of the day just sitting around.
Cormorants are pretty flexible when it comes to nesting locations. They’ll use trees when available, but will also build their nests, mostly of sticks and other vegetation, on the ground. They prefer isolated islands, like Potato Island on Lake Vermilion, where they are generally protected from animal predators.